Thread: Including file containing a custom function

Hi,

I am new here, and I am a beginner in C coding, and I hope you can help me to understand better. I am reading the book An Introduction to GCC by Brian Gough. I don't understand a part where the program "hello world" has been split in three files:

Here I post the code:

file (1) main.c:

Code:

#include "hello.h"

int main (void) {
   hello ("world");
   return 0
}

file (2) hello_fn.c:

Code:

#include <stdio.h>
#include "hello.h"

void hello (const char * name) {
   printf ("Hello, %s\n", name);
}

file (3) hello.h:

Code:

void hello (const char * name);

I understand everything in the code, but, in what way the file hello_fn.c has been included in the program? and therefore why is it possible to use the custom function hello, even if in the source I can't see any inclusion for the file hello_fn.c?

please, can you give me any suggestions? many thanks really!!

Ok, here source is written to be converted to object. so, files with .c extensions should be converted object. (source to object)
after which both object files ".o" can be compiled into single executable file.

to run the code :

gcc -c hello_fn.c main.c
gcc -o main.exe hello_fn.o main.o

If you use Integrated Development Environment, it automatically does it for you..

Originally Posted by kr007

after which both object files ".o" can be compiled into single executable file.

so if I understand, I have not to "include" the file hello_fn.c, because, when we proceed to create an executable file, all the functions and variables, etc... after compiling they will look like as written in a unique file.